Fig. 6: Altered Ca2+ handling underlies NAA10R4S/Y cardiomyocyte dysfunction.
From: Dysregulation of N-terminal acetylation causes cardiac arrhythmia and cardiomyopathy
a Micro-patterned iPSC-CMs loaded with Fura-2 were electrically paced at 1 Hz. Diastolic Ca2+ levels are indicated by arrows between the baseline and dashed lines. b End-diastolic Ca2+ levels were measured at 0.5 Hz and 1 Hz pacing (0.5 Hz: 0.044 ± 0.022, 0.085 ± 0.014, 0.054 ± 0.009; 1 Hz: 0.038 ± 0.007, 0.229 ± 0.029, 0.176 ± 0.017 in WT-, pNAA10R4S/Y-, and eNAA10R4S/Y-iPSC-CMs). Significant differences were observed at 1 Hz for WT vs. pNAA10R4S/Y (p < 0.0001) and WT vs. eNAA10R4S/Y (p < 0.0001) (n = 3, 3, and 3, independent differentiation experiments; p < 0.0001; mixed-effects analysis). c The baseline to peak height of Ca2+ transients paced at 1 Hz (WT = 23.6 ± 2.3 % vs pNAA10R4S/Y = 29.0 ± 2.8 %, and eNAA10R4S/Y = 32.4 ± 3.1 %; n = 15, 18, and 26, independent experiments; n = 3, 3, and 3, independent differentiation experiments; p = 0.2913; Kruskal-Wallis test). d Ca2+ transient relaxation coefficient τ from the same samples in c: WT = 0.38 ± 0.05, pNAA10R4S/Y = 0.62 ± 0.03 (p < 0.0001), and eNAA10R4S/Y = 0.55 ± 0.02 (p = 0.0008) (p < 0.0001; one-way ANOVA). e Immunoblot of RyR2, SERCA2a (SERCA), phospholamban (PLN), NCX1, and vinculin. f Quantification of RyR2, SERCA, PLN, NCX1, and the SERCA/PLN ratio: RyR2 (1.0 ± 0.1, 6.3 ± 0.6, and 3.8 ± 0.9), SERCA (1.0 ± 0.1, 1.6 ± 0.2, and 1.4 ± 0.1), PLN (1.0 ± 0.1, 2.5 ± 0.2, and 2.0 ± 0.2), NCX1 (1.0 ± 0.1, 0.8 ± 0.2, and 0.7 ± 0.3), and SERCA/PLN (1.0 ± 0.1, 0.8 ± 0.1, and 0.7 ± 0.1) in WT-, pNAA10R4S/Y-, and eNAA10R4S/Y-iPSC-CMs; n = 3, 8, 8, 4 independent differentiation experiments for RyR2, SERCA, PLN, and NCX1; p = 0.0017, 0.0053, <0.0001, 0.0045, and 0.0029; Kruskal-Wallis test) Values were log2-transformed and visualized in a heatmap. Data are presented as mean ± SEM. ****p < 0.0001, ***p < 0.001, **p < 0.01, *p < 0.05, ns = p > 0.05. Source data are provided as a Source Data file.
